Method of welding with gas



Patented Mar.v,10, 1942 UNITED STATES PATE OFFICE Y METHOD oFwE'LnlNcwrm GAS VAnders Rudolf Gunnert,` Lidingo, Sweden, as-

sgnor to Svenskal Aktiebolaget .lator, Stockholm, Sweden, a connu-ationof i Sweden In Sweden July 14, 1938 Application July 6, 1939, Serial No.282,970

1 claim. (c1. 11a-112) In butt weldingwith gas,either rightward welding,ordinary leftward welding, or vertical leftward welding has hithertobeen practised. A characteristic feature of all these methods is thatthe welding iiame is inclined towards the surface of the work piece. Inthe mst-mentioned method, the flame is directed towards the completedweld, and in the two other methods, away from it. In rightward weldingand ordinary leftward welding, the edges of the parts to be welded, in

A the following called the plates, are chamfered at an angle of 30- 45.In vertical leftward welding, in which the weld is made verticallyupwards, the edges o1" the platesl are unchamfered, but this weldingmethod is suitable only for a plate thick.

mentionedtimes t1 and t2 thus coincide and the time required forwelding' between two'given points in the joint not be the total of thetimes t1 and t2, but the longer of these. As a matter of fact,- the.weldertries t make these times Aequal in'order to make' the totalwelding time as short as possi-ble. If he has a wide gap, whichrequires'much ller metal, he holds 'the iiame relatively far away fromthe plate surfaces in the gap and more concentrated on thei rod, in

order that, at the sametime as the plate surfaces in the gap are beingmaintained in a melted state, he will get a sui'cient quantity of meltedY filler metalto ll the gap. If he has anarrow l5 gap, on the otherhand, he holds the dame closer to the gap surfaces.

- The present invention refers to a Welding method which can be madeconsiderably more economical than the methods hitherto known, as theWelding Atime can be very much reduced. This tions are also subjected toa strong heat and v partly melted, as it is impossible to melt thesurface and maintain it in a. melted state during the time required fordepositing the iiller metal without also heating the inner portions ofthe plates. The amount of heat thus transferred to the inner portions ofthe plates, as well as the is an unavoidable loss, at least to a certaindefeature of the method consists in directing the Sl'ee, and whichshould be kept as low. as possible Y 'if the welding is to beeconomical. The surfaces of the plates should, therefore,. be heatedrapidly to melting temperature and the ller metal should be depositedquickly so that as small Vamount of heatlas possible has time to beconmaintained in`a molten state t2. It is evidentV that the shorterthesertimes, the more economica the welding,

method can be practised in welding .in all directions and in allpositions of the work, audit requites no other equipment 'than the oneused in the usual Weldingmethods. The new principal flame substantiallyat right angles to the surface of the work, that is, at right angles tothe longitudinal direction of the joint. In this way,

f the ability of the burning gases topass through amount of heat givenoi to the surrounding an', 30

the gap between the plate edges is the greatest possible, and the gapcan thus be made narrow 4can. thus, :when at right angles to the` joint,be carried deep down in the gap even if the gap is 4D narrow, and inAthat way the hottest partsof thename come as near to the edges of the`gap as possible. The flame vis hottest at a pointalong its' center linejust beyond the tip of the inner cone of the dame. This point thus comescloser -to theV surfaces in the gamthe' narrower the g`apf is. From thisit is evident that the'emission of The time f1, iS kept short if theheating effect 0f the name 011 the p12-te edges is good, and the time t2will beshort if the effect of Vthe ame on the rod of filler material isgood, or if a small quantita7 of ller metal is required. When thewelding has proceeded so far that a state of conheat to the edges of theplates may be highly'increased by the 'ame at a-right angle,

andin this way the time t1 may be reduced, and

the welding may be madecorrespondingly more nuance prevails, the flameheats simultaneously the plate surfaces in the gap and the welding rodconstituting the ller metal. The two above- A5 5, tip or the inner coneof the dame is kept at a economical. It has 'further been 'ascertainedthat the emission ofA heat from the dame to unchamfered edges, oredgeschamfered only to a very steep angle, be the greatest possible if thedistance below the' top surface of the work which is more Ithan onethirdof the plate thickness.

s A.The fact that the gap may be narrow and with 'steep plate surfaces,also involves another advantage, namely, that a. smaller amount of'llermetal is required and thm also a smaller amount 'of heatfor' the meltingof this material, which'is more economical. The welding economy is,

however improved indirectly by the fact Athat thev effect of the flameis more concentrated vfon the melting of thev 'plate edges so that thewelding time, and thus also the losses. are reduced. l,The reducedwelding time also entails other advantages. 'If the-weld is maintainedin a melted statefor a long time, this impairs Vits strength, andtherefore the method according -to this invention' increases thestrength ofthe weld,

. especially its impact resistance, and its lductility.

As a smallerA amount of filler metal is required, which is deposited inonerun and all at once for the. entire depth of the weld, very smalldeforma- -tions ofthe work result.

The present invention will be further described in the following, withreference to the attached drawing of which: a

Fig. 1 is a cross-sectional view illustrating the improved methodaccording to the present inven- I tion.

, Fig. 2 is a4 cross-sectional view taken on the line 2;! of Fig. l.

Fig. 3 is, a crossesectional View taken line 3-3 of Fig. 1.

Fig. 4 is a view similar to Fig. 1, but showing another embodiment of myinvention; and

y on the Fig. 5 shows a still further embodiment.

InV the figures, the plates to be joined are indicated by-referencecharacters I and 2, the plates being separated by a gap 3. A blowpipenozzle 4 produces a flame having an inner cone 5'and an envelope 6surrounding the inner cone. The

flame is carried into the gap, the more heat'will be concentrated'on theplate edges', and the loss heat will be available for melting of thefiller .metaL 'It is most economical to carry the flame deep down in thegap, but the diillculty of obtaining a homogeneous joint increasesrapidly as the gap decreases.

To be able to have a narrow gap it is advisable to have a -high rat-.ofissue of the welding gases in the flame, thatis a so-called hard flame.It

should not, however, be so hard that the molten metal is blown away. Forthe welding of ir a rate of issue of between 130 and 175 rn./s. hasproved to be suitable, the harder lflame being suitable for thin plate,and the smaller rate of issue for thick plates. In welding with the gap'in such a position that the-gravity of the melted welding rod isdesignated by reference character 1. The fused material is, in thefigures, shown by horizontal dashes. In the, ordinary welding methods,the rightward welding method probably being most usual, the flame isheld at a certain acute angle in rela. non to the work ana with the upof the inner cone 5 of the flame relatively far from the surfaces oftheplate edges. The filler metal is to be deposited along the entire areabetween the surfaces, and the surface layer of the plate edges will bemelted down to a relatively great depth. This means that a relativelygreat amolmt of material is maintained in a melted, statesimultaneously..This results in the welding methods hitherto known being uneconomical,and the tensile strength of :lointsmade according to the said. methodswill not be as high as those of joints made according to the presentinvention.

According to'the present invention'the nozzle l is held in such aposition that th'e flame' is at right angles tothe gap, as is shown inFigs. 1 through 3. Duetofthe ability of the flame in this positioritopass through a gap, the gap may be narrow and with substantiallystraight edges. The tip of the cone I of the llame is held within thegap at a distance below the upper surface of at least one-third theplate thickness. Due to theintense heat emitted by'the cone, the surfacelayers of the plate edges are melted quickly, and hence only to a smalldepth, as appears from Fig. 2.` 4Since a large part of the hot gasesfrom the material and the pressure of the flame are not acting in thesame direction to force the melted metal `through the gap, somewhathigher speed of the gas is suitable. l

'I'he rod should be manipulated chiefly in the same manner as in therightward welding, that is, in ciroular or elliptic movements in themolten weld metal. The flame, on the vother hand, should be moved alongthe' gap without lateral movement.

The flame makes a substantial enlargement of Athe gap just in front ofthe melted ller metal.

Therefore, it is also possible' to weld without' .a gap, that is, withthe plates in contact, edge to edge, as shown in Fig. 4, in which casethe flame 40,

cuts an opening for the gases. Instead of unchamfered plate edges, it isof course also possible to chamfer them slightly as shown in Fig. 5.

'I'he welding method according to this invention may beemployed inthewelding of ferrous metals as well as of non-ferrous metals.

AlthoughA thismethod is chiefly intended for Oxy-acetylene welding, itmay be practised also in welding with fuel gases other than acetylene,

-such as Oxy-hydrogen welding, oxy-benzoline.

welding, and the like. This welding method is, as shown in the figures,applied in using a one-flame nozzle.- 'I'he method may also be used,however, with a nozzle having several flames. If the flames are placedone after the other in the gap betweenV the plates,

' an amount of h'eat more concentrated in the center of .the gap will beobtained, and the gap i can, therefore, be narrower than with one flame.This will also be the case if a fiat name extended in .the lengthwisedirection of the gap is used. In these cases, as when only one flameisused, a suitable guiding .device for the blowpipe may be applied sothat the flame, or flames, are kept in the middle of the gap. Thewelding rod, too,

.maybe guided in a suitable manner and possibly also fed automatically.

This method is suitable for both hand-'welding and machine-welding,either. wholly automatic or semi-automatic.

Welding according to this method can be performed with a flame that isneutral or has either -some excess of acetylene or some excess ofoxyfiame plays over the top surface, as shownin Fig.

2, the top surface and upper half of the plates"- .become hotter thanthe bottom surface and lower gen. When using severalfiam, they maydiffer in this regard. The amesmay also differ with regard to theirhardness.

ne or'seve'ral smaller flames may be applied for preheating the Weldingrod. These may have anotherdirection than Vthe flames chiefly acting.upontheplatea audit is notnecessary that they Y have the tip of theirinner cone lying below the plate surface.' Y

Whatds claimed is:

"'.The method of joining metal members havin opposed vsubstantiallyparallel steep edge survac'z'es, by means of butt'welding with a gasflame and fillerv rod, thatinclude's vthe lfollowing steps:

maintaining the ow of gas delivered to said ameat a .pressure to provideysaid iiame with an 'innerelongated cone -into .which the gas issues ata velocity within a range of which the lower 15 limit is of thenorder of130 meters per second; maintaining said edge surfaces in spaced 'apartrelationship at a distance substantially equal to the width of said coneto form a welding channel between said-edge surfaces and to provide worksurfaces'on each side of said channel; maintaining the tip of said conejust infront of said rod and at a level at least substantially one-thirdof ANDERS RUDOLF GUNNERT.-

